"We're monitoring the situation and waiting on further lab results," Nichols-Contella said Tuesday.

No details were available Tuesday on the dates of the deaths or hospitalizations, she said.

Although the Montgomery County patients did not test positive for influenza, this is the heart of the U.S. flu season, which typically peaks in January or February, according to the federal Centers for Disease Control and Prevention.

During the week ending Dec. 7, four states - Texas, Louisiana, Alabama and Mississippi - reported high levels of influenza-like illness, the CDC reported. The levels of activity are based upon the percentage of outpatient doctor visits that are due to influenza-like illness, according to the CDC website.

Flu symptoms can include some or all of these conditions:

Fever or feeling feverish

Chills

Cough

Sore throat

Runny or stuffy nose

Muscle or body aches

Headaches

Fatigue

Some people may have vomiting and diarrhea, although this is more common in children than adults.

The CDC recommends a yearly flu vaccine for everyone 6 months of age and older.